Azeotropic composition and process for attenuating magnetic ink characters



Unitcd States Patent G This invention relates to an azeotropic composition of 1,1,2-trichloro-l,2,Z-tritluot'oethane and chloroform, and

to a process for attenuating magnetizable ink characters on documents such as bank checks by said composition whereby said magnctizable ink characters are rendered unrecognizable by data processing equipment.

Azeotropic compositions of 1,1,2-trichloro-1,2,2-tritluoroethane and each of acetone, methyl alcohol, and methylene chloride are known and have been shown to be useful as specialty solvents, by Eiseman, Jr. in U.S. Patent 2,999,815, by Bennett ct al. in U.S. Patent 2,999,816, and by Bower in U.S. Patent 2,999,817, respectively. While these azeotropic compositions are useful for many of the same general purposes, c.g. as solvents for greases, oils, waxes and the rosin fluxes used in making printed circuits, they vary in solvent power with respect to some other substances, whereby they are not full equivalents of each other for all purposes. For example, the azeotrope of 1,1,2-trichloro-l,2,2-trifluoroethane and methyl alcohol has little or no solvent effect on the magnetic inks employed on bank checks and like documents. On the other hand, the azcotropes of 1,l,2-trichloro-1,2,2-trifluoroethanc and acetone or methylene chloride attack paints, varnishes, lacquers, and the inks (including magnetic inks) that are employed on bank checks and like documents. Accordingly, these latter azcotropic compositions cannot be used where their etfect on such substances would be objectionable.

As disclosed by Buros in U.S. Patent 3,112,151, it is a well known practice to imprint on bank checks and other documents various characters in a socalled magnetic ink so that said documents can be passed through data processing equipment. Said magnetic inks" contain particles of magnetizable substances, preferably substances which have a high magnetic retentivity, in a binder, usually a wax, which is different from the binders of the other inks employed on such documents. The other inks employed on such documents are pen inks, such as ball point pen inks and liquid pen inks, and special printing inks which are designed to smear if attempts are made to alter or erase them, usually due to the presence of easily soluble organic dyes, and are nonmagnetizable. When a document having such magnetizable characters encoded thereon is passed through the data processing equipment, it is subjected to a magnetizing force whereby the magnetizable particles are magnetized, and then to means, responsive to the magnetic force of said particles, which reads and records the data symbolized by said characters.

Also, as disclosed by Buros, it sometimes happens that incorrect magnetizable characters are erroneously encoded on such documents and it is desirable to render the incorrect characters unrecognizable by data processing equipment, and then to encode the correct magnetizable characters on said document. Buros proposes to apply to the erroneously encoded magnetizable ink characters, by means of a daubcr, a solvent which softens or dissolves the binder of the magnetic ink. Some of the magnetic ink is absorbed on the dauber and so removed and, due to the combined action of the solvent and the dauber, some of the magnetic ink is smeared so that the magnctizable particles are distributed over a much larger area of the desirable properties.

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document, whereby the magnetic field of said characters is attenuated and they are unrecognizable by data process ing equipment but may remain visible to the human eye. The solvents disclosed by Buros are flammable and hence constitute a tire hazard, or are toxic, or have other un- Also, the process of applying the solvent by means of a dauber, employed by Buros, is slow and inefficient.

It is known to the art that the removal and attenuation of the magnctizable ink characters can be accomplished most effectively and rapidly by immersing the document in the solvent while it is subjected to ultrasonic agitation. This is accomplished in conventional ultrasonic cleaning or degreasing equipment, various forms of which are well known and commercially available.

It is an object of this invention to provide a novel azeotropic composition which has new and valuable properties. Another object is to provide an azeotropic composition which is valuable as a specialty solvent, particularly for cleaning printed circuits and for removing magnetic ink charatcers from bank checks and like documents without altering other indicia on such documents. A further object is to provide a new and improved process for rendering magnet-izable ink characters unrecognizable by data processing equipment which process employs a new and improved solvent composition. Other objects are to provide a new composition of matter and to advance the art. Still other objects will appear hereinafter.

The above and other objects may be accomplished in accord with this invention which comprises (1) an azeotropic composition consisting of about 92.8% by Weight of 1,1,Z-t-richloro-1,2,2-trifiuor0ethane and about 7.2% by weight of chloroform, and having a boiling point of 47.57 C. at 761.9 mm. Hg pressure; and (2) the process for treating documents, having magnetizable ink characters and nonmagnet-izable indicia thereon, to render the magnetizable ink characters unrecognizable by data processing equipment without deleteriously altering the nonmagnetizable indicia, which process comprises:

(a) Treating said magnetizable ink characters with an azeotropic composition which consists essentially of about 92.8% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane and about 7.2% by weight of chloroform (b) In an amount and for a time sufiicient to dissolve the major proportion of the binder of the magnetizable ink and attenuate said characters.

It has been found that 1,1,2-trichloro-1,2,2-tritluoroethane (CCl FCClF and chloroform (CHCI when admixed in the above proportions, form a minimum boiling point azeotrope which distills at constant composition, the liquid phase and the vapor phase in equilibrium therewith having the same composition. The boiling point of pure 1,1,2-trichloro-1,2,2-trifiuoroethane at 761.9 mm. Hg pressure is 47.80 C. This azeotropic composition is non-fiammable in both the liquid phase and the vapor phase, has a toxicity (estimated) of about 700 MAC, and

a mil dodor which appears to be unobjectionable to most persons.

The azeotrope can be prepared by mixing the two components in the indicated proportions. The azeotrope also may be obtained by careful fractional distillation of mixtures of the two components.

The azeotropic composition'of 1,'1,2-trichloro-1,2,2-trifiuorocthane and chloroform is particularly useful as a specialty solvent for cleaning articles and equipment which are composed, in whole or in part, of plastics or which :have coatings of color-code lacquers, vamishes, and the like, that it is desired to leave unchanged. Such articles include photographic film, fine instruments, electric motors, printed circuits and the like. Pure 1,1,2-trichloro-l\,2,2-trifluoroethane does not attack inks, plaslies, waxes, lacquers or varnishes but also has insutiieicnt solvent power to remove the oils, greases or rosin fluxes that may be on such surfaces or on adjacent parts. Pure chloroform is an excellent solvent for oils, greases, and rosin fluxes, but also attacks waxes, inks, color-code lacquers on electronic equipment, dissolves or swells many plastic parts such as circuit boards and plastic gears and bearings and the like of fine instruments, dissolves insulation on electric windings of motors, attacks and dissolves photographic film bases and emulsions, and is sufficiently corrosive to ruin the finish on highly finished machine parts. On the other hand, the azeotropic composition of this invention is an excellent solvent for oils, greases and rosin fluxes, but does not attack lacquers, varnishes, plastics or any metals, and hence has the advantageous properties of both of the 1,1,Z-trichloro-l,2,2-trifluoroethane and the chloroform, but does not have the disadvantageous properties of either. The azeotropic compositions of U.S. Patents 2,999,815 and 2,999,817, hereinbefore referred to, do not have these advantageous properties and hence are not useful where their effect on lacquers, varnishes, plastics, and metals would be objectionable.

Due to the novel combination of advantageous prop erties of the azeotropic composition of this invention, such composition is particularly useful as a solvent as the final rinse in a vapor phase degreaser for removing the rosin flux from printed circuit boards which include parts or portions having coatings of color-code lacquers which it is desired to leave unaltered. It is also particularly useful for dip cleaning, ultrasonic cleaning or vapor phase degreasing of other electronic equipment or fine instruments, such as precision bearings and other high tolerance parts composed of plastic or of both metal and plastic, where it is desired or necessary to avoid attacking the plastic, color-code lacquers, corrosion of very smoothly machined metal surfaces, and the like.-

The composition of the azeotrope of 1,1,2-trichloro- 1,2,2-trifluoroethane and chloroform is critical and has distinct advantages over other mixtures of these two components in materially different proportions. When used in liquid phase cleaning operations, partial evaporation of the azeotropic does not change the composition of the liquid. Partial evaporation of other mixtures of these compounds results in liquids which contain higher proportions of chloroform. Such liquids would eventually attack plastics, color-code lacquers, other inks (in addition to magnetic inks), and the like. When used for vapor phase cleaning operations, this azeotrope offers the advantage of constant composition. When the liquid azeotrope in a container is vaporized for the vapor cleaning operation, the composition of the azeotrope vapor remains constant just as a pure compound would behave. Other mixtures of these compounds in materially different proportions would, under the same conditions, give vapors of varying composition since the more volatile component would vaporize first. This would lead to the same difiiculties as encountered with liquid cleaning operations.

Solvent power is often expressed in terms of the Kauri- Butanol values, solvent power increasing with increas ing values. This test is described in ASTM-Dll33. 1,1,2-trichloro-1,2,2-trifluoroethane has a Kauri-Butanol value of 31, the azeotrope of this invention a value of 44, and chloroform 21 value of 208. Hence, the azeotrope is a somewhat stronger solvent than pure 1,1,2-t-richloro- 1,2,2-trifiuoroethane, but a much weaker solvent than pure chloroform.

' It has been found that the azeotropic composition of this invention is very effective to dissolve and remove magnetic ink from documents, such as bank checks and the like, and does not attack other matter imprinted on or in such documents, such as printed matter, water marks, seals, and writing. Therefore, the magnetic ink charac- .ters are readily removed from such documents by the .method of Euros or, most conveniently, by immersing .the document or any desired part thereof in the azeotropic from the paper.

printed on such documents whereby, when they are used in such process, they cause a smearing of other printed and written matter on such documents, whereby they are not suitable for use in such process.

Due to its new and unusual combination of properties, the azeotropic mixture of 1,1,Z-trichloro-1,2,2-trifluoroethane and chloroform is particularly valuable for use in treating documents having magnetizable ink characters thereon by the solvent removal or attenuation of only those characters so that they are no longer recognizable by data processing equipment. The azeotropic composition can be applied in the manner and by the method disclosed by Buros, e-.g. by means of a dauber. However, the azeotropic com-position is peculiarly adapted for use in an immersion process wherein at least that part of said document which contains the magnetizable ink characters is immersed in the azeotropic composition and maintained in the composition for a period of from about 5 to about 60 seconds, that is, until said characters are removed or attenuated to the desired extent. The document will then be removed from the composition, most of the composition drained off, and the rest allowed to evaporate. The process may be used before or after the magnetizable particles have been magnetized.

By such immersion process, approximately or more of each magnetizable ink character, including the magnetizable particles, is efficiently and rapidly removed cleanly from the document (usually in about 5 seconds), without smearing of the magnetizable character or otherwise altering the document or the other, nonmagnetizable indicia thereon even on long exposure, e.g. 1 minute. Any magnctizable particles left in or on the document are so few in number that said character is attenuated and unrecognizable by data processing equipment.

The speed and efficiency of the removal of the magnetizable ink characters is improved by subjecting the azeotropic composition to agitation during the immersion of the document therein. Preferably, ultrasonic agitation will be used, whereby particularly efficient and rapid removal of the magnetizable ink characters will be accomplished. Thus, the process preferably will be carried out in ultrasonically agitated cleaning equipment which are well known and are readily available commercially. Usually and preferably, the whole document will be immersed in the azeotropic composition, particularly where the document is small as in the case of bank checks. However, where the document is large or bulky so that it cannot be readily immersed completely in the azeotropic composition or where it is otherwise undesirable or inconvenient to immerse the whole document, only that part of the document which contains the magnetizable ink characters and such other parts thereof as desired may be immersed in the azeotropic composition.

Magnetic inks are composed of magnctizable particles of iron or iron compounds dispersed or dissolved in a binder which is a wax or a special resin, usually a wax. When treated with the azcotrope, the binder is softened and partially dissolved. The agitation then causes the ink and particularly the magnetizable particles to separate It is necessary to remove sufficient of the magnetizable particles so that the magnetic reading device will no longer detect their presence. Removal of the binder is of secondary importance. Any form of agitation which causes the separation of the magnetizable particles is useful; the ultrasonic devices, due to their highly efiicient agitation, are convenient and preferred. A high speed spray of the azeotrope directly on the magnetic ink printing also provides sufiicient driving force to remove the magnetizable particles and works well. To remove the magnetic ink, the portion of the document containing the undesired printing is immersed in the azeotrope while the latter is agitated. Immersion for about 5 to about seconds is usually sufficient to remove greater than 75% of the ink and render the magnetizable ink characters unrecognizable by data processing equipment. It is possible to remove all of the ink in this manner, whereby the printing would no longer be legible. Usuaily this is not required and traces of the ink may remain, sufiicicnt to see and perhaps read although not for the magnetic reader to detect. After cleaning, the document is allowed to air dry a few moments, then the correct numbers can be printed.

The process ordinarily will be carried out with the azeotropic composition at about normal atmospheric -tempera ture, i.e. about 21 C. The time of immersion of the document in the azeotropic composition will depend upon the efficiency of the agitation and the results desired. Usually, the time of immersion will vary from about 5 to about 60 seconds, preferably about 5 to about 15 seconds with efiicient ultrasonic agitation. Longer times may be employed, but usually will be unnecessary.

In order to more clearly illustrate this invention, a preferred mode of practicing it, and the advantageous results obtained thereby, the following examples are given wherein the parts and proportions are by weight except where specifically indicated otherwise.

Examples A commercially available, ultrasonically agitated cleaning device ('v\"estinghouse Ultrasonic Cleaning Unit, type Model #7507765-G, of 1 gallon capacity, tray type 8".X 7" X 6", having a magnetostrictive-space-laminatcd transducer), was filled to operational capacity with the 1,1,2 trichloro-l,2,2 trifluoroethane/chloroform azeotrope, or, for purposes of comparison, with other sollvents. Commercial bank checks having magnetic printing and pen ink writing thereon were immersed for 5-15 seconds in the unit with ultrasonic agitation in operation. The checks were then removed, allowed to dry and examined for sufficiency of removal of magnetic ink and the extent of smearing and/or removal of printing and pen inks. The results obtained are shown in the table below. Similar tests were carried out with the other solvents or solvent combinations shown in the table with the results indicated.

Ethylene dichloride CFCL;

CzFaCla/tictttone azeotrope (U.S.

OzFsCla/Bl-llflllOl azeotrope Stoddard Solvent CzlsCl:

n-IIeptanc u-Ilexane Also, a mixture of parts by weight of l,l,2-trichloro 1,2,2-trilluoroethane and 20 parts by weight of methyl chloroform, CH CCl which is not an azeotropic composition, was similarly tested. Initially it was effective to remove and attenuate and magnetizable ink characters without affecting the other inks. However,,during standing and use, the l,t,2-trichloro-l,2,2-trifluoroethane preferentially evaporated so that the mixture became progressively richer in methyl chloroform, whereby after one hour of continuous use, the mixture caused smearing of other inks of the bank cheeks. It was also found that both the initial and the final mixtures were undesirably slow in drying and had a strong and irritating odor. Methyl chloroform has a toxicity value of about 350 MAC. Similarly, the azeotrope of 1 ,l,2-trichloro-l,2,2- trifluoroethane and methylene chloride. of US. Patent 2,999,8t7 has an objectionably strong odor.-

It will be understood that the preceding examples and the specific uses and techniques of using the azeotropic composition of this invention have been given for illustrative purposes solely, and that this invention is not limited to the specific embodiments described therein. On the other hand, it will be readily apparent to those skilled in the art that, subject to the limitations set forth in the general description, the azcotropic composition of this invention can be used for a wide variety of purposes and that the methods and techniques employed and the documents and other articles treated can be widely varied without departing from the spirit and scope of this invention.

From the preceding description, it will be apparent that this invention provides a novel azeotropic composition which has new, unobvious and unexpected properties, whereby it is useful for a variety of purposes for which other related compositions are not useful. Particularly, the azeotropic composition is uniquely valuable for use in attenuating magnetizable ink characters on documents and rendering them unrecognizable to data processing equipment, whereby its use for that purpose provides a new and improved process for the substantial elimination of those characters from such documents. Accordingly, it will be apparent that this invention constitutes a valuable contribution to and advance in the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An azeotropic composition consisting of about 92.8% by weight of l,l,2-trichloro-l,2,2-trifluoroethane and about 7.2% by weight of chloroform, and having a boiling point of 47.57 C. at 761.9 mm. Hg pressure.

2. The process for treating documents, having magnctizahle ink characters and monmagnetizable indicia thereon, to render the magnetizable ink characters unrecognizable by data processing equipment without deleteriously altering the nonmagnetizable indicia, which process comprises (a) immersing at least that part of said document which contains the magnetizable ink characters in an azeotropic composition which consists essentially of about 92.8% by weight of 1,1,2-trichloro-1,2,2-trifiuoroethane and about 7.2% .by weight of chloroform (b) in an amount and 'for a time sufiicient to dissolve and remove the major proportion of the magnetizable ink and attenuate said characters.

3. The process for treating documents, having magnetizable ink characters and nonmagnetizable indieia thereon, to render the magnetizable ink characters unrecognizable by data processing equipment without deleteriously altering the nonmagne'tizable indicia, which process comprises (a) immersing at least that part of said document which contains the magnetizablc ink characters in an azeotropic composition which consists essentially of about 92.8% by weight of l,l,2-trichloro-l,2,2- tritluoroethane and about 7.2% by weight of chloroform, and

(b) maintaining said part of said document in said azeotropic composition for a period of from about 5 to about 60 seconds while subjecting said azeotropic composition to agitation.

4. The process for treating documents, having magnetizable ink characters and nonmagnetizable indicia thereon, to render the magnetizable ink characters unrecognizable by data processing equipment without deleteriously altering the nonmagnetizable indicia, which process comprises (a) immersing at least that part of said document which contains the magnetizable ink characters in an azeotropic composition which consists essentially of about 92.8% by weight of 1,1,2-trichloro-1,2,2-trifiuoroethane and about 7.2% by weight of chloroform, and

(b) maintaining said part of said document in said azeotropic composition for a period of from about 5 to about 60 seconds while subjecting said azeotropic composition to ultrasonic agitation.

5. The process for treating documents, having magnetizable ink characters and nonmagnetizable indicia thereon, to render the magnetizable ink characters unrecognizable by data processing equipment without deleteriously altering the nonmagnetizable indicia, which process comprises (a) immersing at least that part of said document which contains the magnetizablc ink characters in an azcotropic composition which consists essentially of about 92.8% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane and about 7.2% by weight of chloroform, and

(b) maintaining said part of said document in said azeotropic composition for a period of from about 5 to about 15 seconds while subjecting said azeotropic composition to ultrasonic agitation.

References Cited by the Examiner UNITED STATES PATENTS 2,923,747 2/1960 Rapp 252171 XR 2,999,817 9/1961 Bower 25217Z 3,112,151 11/1963 Buros 134-42 3,167,514 1/1965 Baker 252171 XR LEON D. ROSDOL, Primary Examiner.

JULIUS GREENVVALD, ALBERT T. MEYERS,

Examiners. J. T. FEDIGAN, Assistanl Examiner. 

1. AN AZEOTROPIC COMPOSITION CONSISTING OF ABOUT 92.8% BY WEIGHT OF 1,1,2-TRICHLORO-1,2,2-TRIFLUOROETHANE AND ABOUT 7.2% BY WEIGHT OF CHLOROFORM, AND HAVING A BOILING POINT OF 47.57*C. AT 761.9 MM. HG PRESSURE. 